Actigraphy devices measure gross motor activity of a body by deploying motion sensors that may be worn in a variety of places and that may include a wrist (in a watch-like device), leg, shoulder, chest, or some other part of the body. Actigraphy data may be analyzed to determine rest and activity patterns of a person (in this description, the “subject”) wearing, or otherwise being sensed by, the device. For example, actigraphy data can be analyzed to evaluate insomnia, to identify restless legs syndrome, to determine levels of daytime physical activity, to assess treatments for sleep disorders, and for other purposes. The determination of sleep timing obtained from actigraphy data may be useful for additional purposes such as assessing whether a subject is receiving enough sleep and estimating at which times the subject is most likely to be subject to the highest risk for fatigue-related incidents.
In certain industries, or for clinical purposes, there may be a desire to collect actigraphy data for a specific subject. By way of non-limiting example, in the trucking industry, actigraphy data may be used to ensure that truck drivers are receiving an adequate amount of sleep. One potential problem with collecting data without oversight of a laboratory environment is that the people on whom such data is being collected may transfer the device, whether mistakenly or intentionally, to another individual thereby corrupting the process of accurate data collection. For example, if a truck driver anticipates receiving less sleep than is necessary for demonstrating readiness for work, he may ask another person that maintains a normal sleep schedule to wear the data-collection device. If the only data collected is actigraphy data, it may be difficult to determine whether the subject that wore the device during a data-collection period was the intended subject.
There is a general desire to collect sleep history information that is accurate and can be reliably associated with a specific subject in a manner that is more robust that using only self-reported subject identity.